time devoted per dollar earned
let's look at the categories
1) adsense sites
2) affiliate sites
3) selling your own product
4) selling an affiliate product to your list
time devoted in all cases is the total time to build the sites, generate traffic, build the lists etc
my instinct tells me number 4 is the fastest way to big bucks, it's just that initial progress is slow with building a list until you have enough subscribers to ad swap